AES E-Library

AES E-Library

All-Pass Linear Arrays

When using multiple drivers in a linear array structure to achieve an increased soundfield level, the designer must consider the spatially dependent frequency response of the array. By using specifically designed weights for the array elements, the array can be made to have a spatial all-pass characteristic such that there is minimal variation in the frequency response of the array with respect to angle. Weights that achieve this property correspond to FIR filter approximations of all-pass filters. A search algorithm for such approximations is described, and examples are provided to demonstrate the design freedoms of the proposed approach, including the use of crossover-filter configurations.